Fabrication of stacked color converter for high-power WLEDs with ultra-high color rendering

Abstract

White light-emitting diodes (WLEDs) with high color rendering is strong required in some color-critical lighting applications. However, developing a stable color converter with broad emission remains an outstanding challenge for high-power WLEDs. Herein, a stacked color converter of red CaAlSiN3:Eu2+ (CASN) phosphor-in-silicone (PiS) layer coated on a green Y3Al3.08Ga1.92O12:Ce3+ (YAGG) phosphor-in-glass (PiG) was fabricated to realize ultra-high color rendering for high-power WLEDs. The YAGG PiG was prepared by printing and sintering the mixture of YAGG phosphor and borosilicate glass matrix, and then the CASN PiS layer was coated the YAGG PiG. The PiS thickness was controlled to adjust the luminescence of converters. The converter exhibits a broad emission due to the compensation of cyan valley. The converter enables a pure white light with an ultra-high color rendering (Ra = 96.1, R9 = 90.1, R13 = 98.5; Rf = 92, Rg = 100) and chromaticity coordinates (0.367, 0.372). The WLED achieves stable color quality under various driving currents.